Systematic investigations of high-pressure polymorphs in shocked ordinary chondrites

Masaaki Miyahara, Akira Yamaguchi, Masato Saitoh, Kanta Fukimoto, Takeshi Sakai, Hiroaki Ohfuji, Naotaka Tomioka, Yu Kodama, Eiji Ohtani

Research output: Contribution to journalArticlepeer-review

Abstract

Shock-induced melting textures and high-pressure polymorphs in 178 ordinary chondrites of all chemical groups and petrologic types were investigated. The shock-induced melting modes were classified into three types, namely pocket, line, and network. The type of shock-induced melting depends on the petrologic type. The width of the shock-induced melt increased with increasing the petrologic type number. The approximate estimated shock-pressure ranges recorded in and around the shock-induced melts of the H-group ordinary chondrites based on the identified high-pressure polymorphs were as follows: H3, less than 2 GPa; H4–H6, 2–6 GPa. For ordinary chondrites of the L/LL group, the values were as follows: L/LL3, 2–6 GPa; L/LL4, 2–14 GPa; L5: 14–20 GPa; LL5, 2–14 GPa; L6, 17–23 GPa; and LL6, 14–18 GPa. After adopting the estimated shock pressures into the onion shell-structured parent body model, the shock pressure on the surface was much lower than in the interior. One possibility is that the apparent lower shock pressure on the surface is due to spallation during the impact. Considering the features of the high-pressure polymorphs, the major disruption history of the parent bodies is different in each chemical group, although the L/LL chondrite parent bodies may have a similar major disruption history.

Original languageEnglish
Pages (from-to)2619-2651
Number of pages33
JournalMeteoritics and Planetary Science
Volume55
Issue number12
DOIs
Publication statusPublished - 2020 Dec
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

Fingerprint

Dive into the research topics of 'Systematic investigations of high-pressure polymorphs in shocked ordinary chondrites'. Together they form a unique fingerprint.

Cite this